The invention relates to a method of aeration particularly by gentle diffusion, but not exclusively, intended for the aeration of a passenger compartment of a motor vehicle, as well as an aeration device for the implementation of such a method.
The aeration within the passenger compartment of a motor vehicle is usually performed by air blown through a plurality of directional nozzles. These installations exhibit several major drawbacks: they produce air currents, a non-uniform distribution of the temperatures, thermal differences between the front seats and the rear seats of the vehicle, and a sensation of thermal instability. The comfort of the passengers is therefore substantially affected by this.
In order to overcome these problems, a solution called xe2x80x9cgentle-diffusionxe2x80x9d solution consists in diffusing the air through an air-permeable surface of the dashboard. These surfaces are prepared in the form of porous materials, of a grating or of a large number of holes piercing a surface which is impermeable to air. The patents EP 0 713 792, FR 2 074 471 or U.S. Pat. No. 1,140,469 disclose various embodiments of gentle-diffusion structures.
However, these structures feature air-permeable surfaces which are either too permeable, and the speed of the air at the air-diffusion nozzles associated with the gentle diffusion is then too low, or not permeable enough, in which case the loss of pressure head is too great. In these conditions the dynamic range for temperature regulation of the passenger compartment is too small, while the time taken to regulate the temperature of the vehicle is too long, which detracts from the comfort of the passengers, in particular of the passengers situated in the back.
In order to overcome this problem, the invention proposes to regulate the speed of the gentle-diffusion air in a range of values optimized to allow a layering of the air towards the top of the passenger compartment in such a way as to obtain a uniform atmosphere in the whole passenger compartment.
More precisely, the object of the invention is a method of aeration by gentle diffusion for ventilation, heating and/or air-conditioning of a passenger compartment, in which, at the maximum of the ventilated-air throughput, the proportioning of the diffusion is regulated to even out the diffused air to a speed lying between substantially 1 and 5 m/s, and preferably between substantially 2 m/s and 4 m/s on leaving the diffuser.
According to one particular embodiment, the method consists in combining, with the mode for gentle diffusion of the air, an aeration by directional ventilation. This embodiment makes it possible to have the possibility of adding to the ambient sense of comfort, obtained by making the gentle-diffusion air uniform, an additional sense of comfort by an additional supply of air blown in at various points. Furthermore, in order to control the throughput of air for the aeration, it is proposed to carry out the regulation of this throughput at the location of central control of the aeration, whereas, according to the state of the art, this regulation is carried out at the outlet, at the location of each aeration nozzle. This amounts to regulating the distribution between gentle and directional diffusion upstream of the outlet pipework.
In these conditions, the function of opening/closing of the aerators is no longer necessary, which simplifies the design and the fabrication of the aeration function, bringing a possible financial saving. Furthermore, dispensing with the flap at the final stage of the aeration makes it possible to free the design (the shape) from the technical constraints, facilitating, for example, the matching of the aerators to the shapes of the driver""s position. This has the added advantage of allowing a saving of space by dispensing with the knurled regulating wheels, as well as an improvement in the noise level in the passenger compartment.
The invention also relates to a device for aeration of a passenger compartment including at least one fan and at least one duct for gentle diffusion of the air, having at its open end an air-permeable panel which provides for a gentle diffusion of the air in the passenger compartment, and in which the duct and the porosity of the panel are dimensioned so that, at the maximum ventilated-air throughput, the speed of the diffused air lies substantially between the values mentioned above.
The dimensioning relates especially, at maximum ventilation speed, to the aperture at the end of the duct, that is to say the dimensions of the panel and/or the porosity of the latter. The porosity corresponds to the resistance to the passage of air through the panel. This resistance is dependent, especially, on the dimension, the density and/or the shape of the holes.
According to one particular embodiment, the device furthermore includes at least one aeration duct, this duct being dimensioned so that, at the maximum air throughput blown by the fan, the speed of the air at the location of the aeration nozzles lies substantially between 2 m/s and 10 m/s, and preferably substantially between 4 m/s and 8 m/s.
According to other embodiments, the device, intended for a passenger compartment of a motor vehicle equipped especially with glazing, includes at least two air-diffusion ducts suitable for separating an airflow, originating from a common duct situated upstream, into at least two secondary airflows for the gentle diffusion of the passenger compartment and for the de-icing of the windscreen.
In order to reduce the turbulence phenomena, limit the thermal losses and the acoustic reflections and therefore the noise, the output angle xcex11 of the gentle-diffusion duct (4) with respect to the dashboard advantageously lies between 0xc2x0 and a maximum value xcex12 equal to the angle of inclination of the windscreen to the dashboard increased by 30xc2x0.
When the device includes at least one aeration duct combined with the gentle-diffusion duct, these ducts are advantageously dimensioned so that the air throughput of the duct for the gentle diffusion of the passenger compartment lies between 50% and 95% of the throughput of the common duct, while the air throughput of the duct or ducts for the aeration lies respectively between 50% and 5% of the throughput of the common duct.
The invention thus makes it possible considerably to improve the comfort of the passengers by achieving a dynamic range of regulation of the temperature of the vehicle, achieving stability of the temperatures, thermal comfort and a particular skin-surface sensation of the air speeds.
According to particular embodiments, with the aeration by directional ventilation being carried out through at least two aeration ducts coupled to the common section, each aeration duct includes a flap for regulating the air throughput, substantially upstream of the outlet. When the aeration ducts divide into secondary ducts, the throughput regulation is carried out by flaps common to the secondary ducts in common-access or separate-access control mode, i.e. by flaps arranged at the inlet of each secondary duct.
In these conditions, a reduced volume is given over to the aerator function with regard to the state of the art which provides flaps at the end of the aeration ducts. Moreover, the arrangement of a flap upstream of the air outlet makes it possible to avoid the variations in orientation of the nozzles and therefore of the airflow at the outlet. Furthermore, this repositioning of the flap in the duct leads to an appreciable acoustic improvement.